Electricity-Paper 1

Question 1

What is current

Answer 1

Current is the rate of the flow of charge

Question 2

What is potential difference

Answer 2

Energy per unit charge

Question 3

What is a series circuit

Answer 3

One path for current to flow

Question 4

What is a parallel circuit

Answer 4

More than one path for the current to flow

Question 5

How does current behave in a series circuit

Answer 5

Same value at any point

Question 6

How does Potential difference act in a series circuit

Answer 6

Shared

PD added up is the same is the PD from the source

Question 7

Effect of adding a resistor in series

Answer 7

Total resistance is increased

Question 8

How does current behave in a Parallel circuit

Answer 8

The current is shared between branches

Question 9

How does potential difference behave in a parallel circuit

Answer 9

The PD is the same across all components

Question 10

What is the effect of adding a resistor in a parallel circuit

Answer 10

Reduced the total resistance

Question 11

What does an I-V graphic show

Answer 11

Shows how the current flowing through a component changes as the potential difference across it increases

Question 12

What is a national grid

Answer 12

A system of cables and transformers that connects power stations to consumers

Question 13

Describe the I-V graph of an ohmic conductor

Answer 13

The current through an ohmic conductor at constant temperature is directly proportional to the potential difference

Question 14

Describe the I-V graph it a filament lamp

Answer 14

As the current increased the temperature of the filament lane increases

The atoms in the filament vibrate more

Resistance increases

Question 15

Describe the I-V graph of a diode

Answer 15

Current will only flow through a diode in one direction

The diode has a very high resistance in the opposite direction

Question 16

What is a LDR

Answer 16

A resistor that depends on light

Question 17

What is a thermistor and the effect on heat on resistance

Answer 17

A resistor that depends on temperature

The higher the temperature the lower the resistance

Question 18

Describe mains electricity

Answer 18

Mains electricity is an AC supply

Frequency of 50Hz

PD of 230v

Question 19

What happens to the current and PD in a step up transformer and step down

Answer 19

Step up:PD increases
Current Decreases

Stepdown:Opposite

Question 20

Why does the National grid use transformers

Answer 20

Lowers the current to reduce any heating of the transmission cables

This means PD has to increase

Reduce PD after to make it safe for consumers

Question 21

What is an electrical field

Answer 21

A region around a charged object where there can be a non contact force

Question 22

What forces occur between charged objects

Answer 22

Non contact forces occur between charged objects

Opposite charges attract each other

Question 23

What is static electricity

Answer 23

When two different insulators are rubbed together

Electron may transfer from one material to another

A positive Static electricity forms when an object loses electrons

A negative Static electricity forms when an object gains electrons

Question 24

How can you discharge an object to prevent sparking

Answer 24

By being earthed

Question 25

How does the strength of the electric field vary with distance from the charged object

Answer 25

The electric field gets weaker as the distance increases